<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>透明度</title>
  <style>
    div {
      width: 500px;
      height: 500px;
      background-color: orange;
      opacity: 0.5;
    }
  </style>
</head>

<body>
  <div><img src="../images/phone.png" alt=""></div>
</body>

</html>